The slight decrease in Australia's TFR between 2008 and 2009 was the result of the decline in the age-specific fertility rates for all age groups, except for women aged 40-44 years for whom the fertility rate increased, and women aged 45-49 years for whom the fertility rate remained the same.

Over the past few decades, the decline in Australia's TFR has been associated with the tendency for women to have their babies at older ages. The median age of all women who registered a birth in 1999 was 29.7 years; by 2006 this had increased to 30.8 years and has since declined to 30.6 years in 2009.

Until the late 1970s, the distribution of fertility rates across age groups was relatively stable, with each age group peaking and troughing together, although peaks were more pronounced for some age groups than others (graph 2.2). Women aged 25-29 years have had the highest fertility rates over the past 80 years, followed by women aged 20-24 years. Over the past two to three decades, fertility rates amongst younger women have been declining.

The transition to an older age-specific fertility pattern is illustrated by the shift in peak fertility rates, from women aged 25-29 years in 1999 to women aged 30-34 years in 2000. Since then, women aged 30-34 years have continued to record the highest fertility rate of all age groups, with 124 babies per 1,000 women in 2009. Further, since 2003 the fertility rate for women aged 35-39 years has exceeded that of women aged 20-24 years.